Sourland Mountain Preserve

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Hike over boardwalks and through the boulders of Devil’s Half Acre and Roaring Rocks.

5.4 miles. The Ridge Trail is very rocky with some minor elevation gain. Mountain biking, horseback riding, and bouldering are also allowed.

  • Shorter: 5.0 miles – follow only the SQUARES of the Ridge trail
  • Short: 1.4 miles “Maple Flats” (TRIANGLE only), and .5 miles Pondside (CIRCLE only).
  • Also: There are several trails marked “C” (Connecting) throughout the park, which can be used to shorten the hike at several points.
  • Nearby: Duke Farms; Griggstown Grassland; Sourlands Ecosystem Preserve; Six Mile Run.

Update 1/12/21 – NOTE!!! The park has completely changed the trail system. The trails themselves are unchanged but the names and blaze colors are very different. Until we can update the page, the hike description will not match what you encounter on the trail nor on the new trail map.

Our two cents:

A solid loop with plenty of interesting rock formations. Though the trail requires no scrambling, bouldering is allowed here so energetic hikers can clamber around the big rocks in Devil’s Half-Acre.

Even though it’s called the “Ridge” trail, there are no views from any of the trails. The trail network allows for shorter hikes, but the many “C” connecting trails can add a touch of confusion to the navigation.

From info located online, this appears to be a no-hunting park.


Print out the map from the park site, and maps may be in the trail kiosk. Follow along on a smartphone with our Interactive Map link in the box above.


This route now appears in Best Day Hikes in New Jersey and Hike of the Week. A variation of this hike (Ridge Trail only, 5 miles) can be found in Best Day Hikes Near Philadelphia.

Another variation appears in 60 Hikes Within 60 Miles: New York City but is out-of-date in the area of marker #7 (it’s still a really worthwhile book to get through, lots of great hikes!).

Parking: N40.47380° W74.69425°

East Mountain Road, Hillsborough, NJ 08844. Directions can be found on the park site.


Porta-john in the parking lot.

Updates – 1/2020: Re-hiked, minor description changes. 11/9/17: Re-hiked, minor tweaks, updated GPX, added new fall photos, moved winter/summer photos to the blog posts. 

11/15/14: The unmarked trail that bypasses some switchbacks at marker 7 has been blocked, so that option been removed from the description. 

1/24/13: Since this hike was posted in 2009, the “Roaring Brook Trail” (RED, 2.1 miles) has been added to the park, and the location of Marker 7 moved. The description and GPS file have been updated to reflect the addition, and the route is now longer.

Hike Directions:

Overview: Ridge (WHITE Square) – Roaring Brook (RED Circle) – Ridge (WHITE Square).

There are several trails marked “C” (Connecting) throughout the park, which can be used to shorten the hike. Some trail junctions have numbered signs that correspond to the trail map. 

The trailhead for all trails starts behind the trail kiosk, near the tree line.

Main trailhead

0.0 – Start following Ridge (WHITE Square).

0.2 – Continue straight on Ridge (WHITE Square), passing Marker #1 and a bridge on the left.

0.4 – Continue following Ridge (WHITE Square), passing a “C” Connecting trail on the left.

Ridge Trail

The trail heads uphill and loops around an area of large boulders.

Ridge Trail thru Devil's Half Acre Boulders
Devil's Half Acre Boulders
Ridge Trail marker

There are multiple paths around this area and following the actual marked path can be a bit tricky.

Continue following Ridge (WHITE Square) as it heads to the right, passing the other end of a Connecting trail on the left – though this one was not marked with a C, just the regular Square marker.

Large boulder in Devil's Half Acre
Tree growing out of a boulder

1.6 – Continue following Ridge (WHITE Square) past another “C” Connecting trail on the left.

Shortly, the trail splits in a “Y” at Marker #4. 

At Marker #4, veer right to start following Roaring Brook (RED Circle). [Ridge (WHITE Square) continues off to the left]

Roaring Brook Trail
Rocks of the Roaring Brook Trail
Looking up the Pipeline cut

2.1 – Cross a pipeline cut.

2.3 – Continue following Roaring Brook (RED Circle) past BLUE on the right.

Note/optional: The BLUE trail may still not be on the trail map. On our last hiked we checked it out (1/2020).

It’s just on alternative to keeping on RED and doesn’t change the total hike distance. End up back on this route at 3.0 below. It was worthwhile so if you’ve hiked here before and want to change it up, give the very rocky BLUE section a whirl.

New Blue trail

2.8 – Continue following Roaring Brook (RED Circle) to the right, past another Connecting Trail.

3.0 – Continue following Roaring Brook (RED Circle) past the end of BLUE on the right.

3.1 – Roaring Brook (RED Circle) ends in an area of large boulders. 

Turn right to start following Ridge (WHITE Square). [Ridge (WHITE Square) also goes to the left].

Ridge Trail
Huge cairn near Marker 7, Ridge Trail

3.3 – Marker #7, near a very large cairn (hiker pile-o-rocks). Continue on Ridge (WHITE Square). [A “C” Connecting trail goes left and leads to marker #6].

Follow Ridge (WHITE Square) down several gradual switchbacks before the trail levels out and arrives at an opening in a chain-link fence.

Flat rocks on the trail

3.6 – Walk through the fence opening to Marker #8, and continue straight on Ridge (WHITE Square). [A “C” Connecting trail goes left, also leading to Marker #9]

4.1 – Marker #9. Continue straight on Ridge (WHITE Square).

[A Connecting trail goes left, though it was not marked with a “C”, which leads back to Marker #8. Right goes out to Rt. 601.]

Pass stone remnants of a structure. There are several boardwalks and stone pathways in wet areas.

Boardwalk on the ridge trail
Bridge on the ridge trail

4.7 – Marker #10. Turn RIGHT, following Ridge (WHITE Square). [Trail now co-joined with Maple Flats (Triangle) but you may not spot markers].

Marker 11, Ridge Trail

5.1 – Marker #11 [Also marked with Maple Flats (Triangle)].

Crossing the pipeline again

Cross the pipeline cut and Ridge (WHITE Square) continues on the other side.


5.3 – Marker #12. Continue on Ridge (WHITE Square). [Co-joined with Maple Flats (Triangle) and Pondside (Circle)].

Turn RIGHT and head towards a pond on a grassy area in a field. At the pond, the parking lot will be visible off to the left.

Approaching the pond near the parking lot

Hiked: 1/1/20. Variation; using Blue. Same mileage.
Hiked: 11/4/17.
Hiked: 11/14/14. Variation; skipped Roaring, stayed on Ridge. 5.3 miles.
Hiked: 1/19/13. Trail Blog: “Sourland Mountain Preserve in Winter
Hiked: 8/8/09. Trail Blog: “Sourland Mountain Preserve in Summer